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Pipe in Plate Underfloor Heating Installation Instructions

Pipe in Plate Underfloor Heating Installation Instructions

Easy to Install Pipe-in-Plate System 

Warm water pipe-in-plate central heating systems are easy to install.  A high degree of components prefabrication and attention to detail ensure fast and problem-free installations.  The ALUPERT pipe is pushed into plates at predefined spacing and connected to the Manifold, which is then ready for connection to the heat source.  All types of boilers or sources of warm or hot water can be used. Floor Heating systems are ideally suited to condensing boilers for further saving in running costs. 

Aluminium plate system does not require any special tools to fix the heating pipe into the plate, only a saw for notching joists.


1- Site preparation

The following points must be observed before starting installation.


1- Aluminium plate system must be installed in timber joist floors.

2- Plates are 395mm x 1250mm approx. to fit directly on to joists with centres at 400mm and 595mm x 1250mm to fit on Joists at 600mm.

3- It is important that the plate is fitted so it is in direct contact with the underside of the timber floor with no air gap. The insulation should be fitted tight between the joists directly below the plate. On ground floors with vented solum a visqueen sheet should be laid over the plates prior to laying the timber floor.

2- Distribution Manifold

The manifold is assembled and fixed to the walls or in a cabinet. The top section (the return) is approximately one metre above floor level.

Manifold on wall ready for pressure testing

Connect the flow and return to the manifold as shown in the diagram.  Electric cables from the boiler, programmer and room thermostats should also be in place, and terminate at a junction box near the manifold.

3- ALUPERT Heating Pipe

The pipe is laid , where the flow is always is nearer the outside wall, ensuring even floor temperature and better heat distribution in the room.

Hint:  It is helpful to draw the pipe layout on the floor using large red and blue felt-tipped marker pens taped to either end of a one metre length stick.  The flow for each room is drawn in red starting at the manifold and the blue marker is used when returning from the room.

The pipe layout, spacing, and length per zone is supplied with each project.  The overall length of pipe is arrived at by multiplying pipe density (the inverse of the spacing) by area of room and adding to it twice the distance to the manifold.  Further refinement can be achieved by having the pipes near patio windows spaced closer together, while pipe near internal walls are spaced further apart.  The average pipe spacing for the room remains the same as specified on the drawing.

Make sure that pipes will not cross each other anywhere on the floor and especially near the manifold.  Mark the rooms or zones on the manifold using the provided stickers. The maximum pipe length per zone should not exceed 100 metres.  A zone can cover more than one room.  Corridors are usually heated from the pipes leading to other rooms.  On the other hand, large rooms may require more than one zone per room.

After drawing all the zones on the floor, measure the length of pipe required per zone by using a compact distance measuring wheel (available from us) and write the distance from the manifold on the floor in the middle and at the end of each zone.  The pipe is marked at one-metre intervals and the length should be checked regularly while being laid.

Hint:  If distance-measuring wheel is not available, you can measure the length of zone by 'stepping it'.

Pipe laying starts at flow part of the manifold and fixed to plates.

Hint:  To avoid pipe getting entangled, your helper should uncoil the pipe by rolling the coil on its edge only a few metres ahead of you.

ALUPERT pipe must not be bent to a radius of less than 120 mm. to avoid buckling and damage.

Sometimes the pipe must go through the walls to reach the manifold.  Make sure that part of the pipe is wrapped with insulation or conduit to avoid heat transfer into the wall. Heating pipe is not normally installed under kitchen units, wardrobes or toilet pans, unless specified.

4- Filling and Pressure Testing.

When all zones are installed and connected to the manifold, the system is filled with mains water using a hose. Fill one zone at a time to ensure rapid expulsion of air.  Anti-freeze and inhibitors are added at this stage.  Please follow manufacturers' instructions for type and amount to be used with plastic pipe.

Hint: Fernox Copal is used with aluminium boilers and CP3 with cast iron ones

The system is then subjected to a pressure test (up to 10 bar) to check for leaks in the pipe.  It is normally kept at this pressure overnight and while the floor is screeded if possible. The heating installer's job is complete once the Pressure Test Certificate has been signed and the screeding contractor has been advised of the points below.


Most floor coverings can be used with floor central heating.  However, the response time varies from one type of covering to another.  Floors covered with carpets transmit their heat slower than those covered with tiles. Flat felt type underlay is preferred if used.

Hardwood or parquet wooden flooring can be laid but please contact flooring manufacturer to ensure suitability and follow their installation instructions allow the floor to expand in either direction. Floor surface temperature must not exceed 28 ºC.

Avoid using bitumen-based adhesive for sticking PVC and wood floors.  Use resin type instead in this case.  Normal tile adhesive can be used otherwise.  If in doubt consult manufacturers of the adhesive.


1- The Programmable Electronic Thermostat is wired according to the enclosed circuit diagram.  It operates the two port motorised valve, boiler and circulating pump at the manifold.  Separate rooms or zones can be controlled by zone actuators at the manifold using individual room thermostats (available separately).  All the thermostats supplied have a night 'set-back' facility ensuring good response from the floor central heating.  It is recommended that all electric wiring must be carried out by experienced electricians as a safety precaution.

2- Alternatively Programmer/ Compensator is wired to the servo-motor (at the 4-port valve), the pump and sensor (at the manifold) and optionally to the boiler and internal room thermostat. See enclosed relevant wiring diagram.


Once the floors are laid, the boiler is connected to the system, and all the plumbing is checked for leaks.  The ball valves at the manifold are opened and the air in the system is vented one more time. Floor central heating requires a pressure head of at least 1 bar whenever possible to ensure that the pipes in the floor are free of air.  Unvented sealed circuits using expansion vessel and filling loop with double check valve are best suited to the system.

To operate the system at the optimum setting the following procedure is followed:

1- Set the water temperature control valve situated on the return part of the manifold (marked with blue dot) in mid position, and read temperature gauge (also fitted to the return), when system temperature stabilises (approx. 35oC).  This may take some time.

Alternatively open the 4-port mixer using the manual setting on the programmer/compensator.

2- Now read the temperature difference between flow and return of each zone using a differential thermometer.  The difference should be between 5-10oC. in a stable mode.

3- Adjust the flow lock shield valve, using Allen key to maintain the same temperature difference between zones.  Shorter length of pipe requires the lock shield valve to be closed a few turns more to balance pressure drop and flow rate compared with longer zone pipes.

4- The electric zone actuators replace the hand wheel at the return section of the manifold where required.

5- Measure air and floor temperature in various rooms.  The floor surface temperature should not exceed 30oC.  If it does, close the lock shield valve further for that zone or turn down the water temperature control valve to reduce the overall temperature at the manifold.

Allow several hours for system commissioning as it takes time for the floor to reach required stable temperature.


Your floor central heating system consists of high quality components, is reliable and virtually maintenance-free.  However if you should experience any problems please follow the procedure below.

A - Checks


1.  Delta Programmer - Compensator is in the "on" position.


2.  Or programmable and individual zone/room thermostats are in the "on" position.


3.  Boiler is on.


4.  All circulating pumps are running.


5.  Two port motorised valve is in "open" position, if installed.


6.  Three port motorised diverter valve is in central heating position if installed.


7.  Flow part of manifold (bottom) is warmer than return part (top).


8.  Temperature gauge on return part of manifold is reading between 30 and 50 ºC.


9.  Overall system pressure is between 1-1.5 Bar (a pressure gauge is usually installed next to expansion vessel).


10.  Check system is free of air and all zones are warm.


B - Faults


1.  Servo-motor on 4 port mixer (if installed) should be fully open


2.  Neon light off when programmable thermostat switched on.   


3.  If boiler has not fired.


4.  If circulating pump is not running.


5.  Two port motorised valve is still closed.


6.  If three port valve not switching to central heating.


7.  Flow cooler than return.


8.  Manifold not heating.


9.  If pressure is falling.


10. If some zones are cold.


C - Fault Rectification


1. Check wiring between programmer and servo motor. You may have to swap wires over (See instruction and boiler wiring diagram)


2. Check wiring to thermostat from fused spur (see wiring diagram).


3. Check that a live signal is sent from programmer to thermostat position in boiler (see programmer wiring diagram).


4. Check that pump is wired according to pump at programmer instruction.


5. Check wiring diagram for valve and programmer.


6. Check that cylinder thermostat is off and valve is correctly wired.


7. Check pump and mixer valve are fitted the right way round (see heating circuit diagram).


8. Make sure that all valves are open. These include isolating ball valves, lock shields, hand wheel valves and actuators.


9. Check for all leaks in soldered and compression joints at the manifold and throughout the system. It is easier to detect minute leaks when system is run cold


10. Remove air by shutting all other zones at manifold and open-air vent at manifold while running system at least at 1.5 Bar pressure.


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